Changed how the operating system is provided to Chroot (API change).

* Where before debootstrapped and bootstrapped took a System parameter,
  the os property should now be added to the Chroot.
* Follow-on change to Systemd.container, which now takes a System parameter.

Two motivations for this change:

1. When using ChrootTarball, there may be no particular System that
   makes sense for the contents of the tarball, so don't force the user to
   specify one.
2. When creating a chroot for a disk image with the same properties
   as an existing Host, using hostProperties host to get them, this
   allows inheriting the os property from the host, and doesn't require
   it to be redundantly passed to Chroot.debootstrapped.

1 files changed, 35 insertions, 33 deletions

diff --git a/src/Propellor/Property/Chroot.hs b/src/Propellor/Property/Chroot.hs
index 2b5391fa..f32a9117 100644
--- a/src/Propellor/Property/Chroot.hs
+++ b/src/Propellor/Property/Chroot.hs
@@ -34,25 +34,26 @@ import System.Posix.Directory
 -- | Specification of a chroot. Normally you'll use `debootstrapped` or
 -- `bootstrapped` to construct a Chroot value.
 data Chroot where
-	Chroot :: ChrootBootstrapper b => FilePath -> System -> b -> Host -> Chroot
+	Chroot :: ChrootBootstrapper b => FilePath -> b -> Host -> Chroot
 
-chrootSystem :: Chroot -> System
-chrootSystem (Chroot _ system _ _) = system
+chrootSystem :: Chroot -> Maybe System
+chrootSystem (Chroot _ _ h) = fromInfoVal (getInfo (hostInfo h))
 
 instance Show Chroot where
-	show (Chroot loc system _ _) = "Chroot " ++ loc ++ " " ++ show system
+	show c@(Chroot loc _ _) = "Chroot " ++ loc ++ " " ++ show (chrootSystem c)
 
 instance PropAccum Chroot where
-	(Chroot l s c h) `addProp` p = Chroot l s c (h & p)
-	(Chroot l s c h) `addPropFront` p = Chroot l s c (h `addPropFront` p)
-	getProperties (Chroot _ _ _ h) = hostProperties h
+	(Chroot l c h) `addProp` p = Chroot l c (h & p)
+	(Chroot l c h) `addPropFront` p = Chroot l c (h `addPropFront` p)
+	getProperties (Chroot _ _ h) = hostProperties h
 
 -- | Class of things that can do initial bootstrapping of an operating
 -- System in a chroot.
 class ChrootBootstrapper b where
 	-- | Do initial bootstrapping of an operating system in a chroot.
-	-- If the operating System is not supported, return Nothing.
-	buildchroot :: b -> System -> FilePath -> Maybe (Property HasInfo)
+	-- If the operating System is not supported, return 
+	-- Left error message.
+	buildchroot :: b -> Maybe System -> FilePath -> Either String (Property HasInfo)
 
 -- | Use this to bootstrap a chroot by extracting a tarball.
 --
@@ -63,7 +64,7 @@ class ChrootBootstrapper b where
 data ChrootTarball = ChrootTarball FilePath
 
 instance ChrootBootstrapper ChrootTarball where
-	buildchroot (ChrootTarball tb) _ loc = Just $ extractTarball loc tb
+	buildchroot (ChrootTarball tb) _ loc = Right $ extractTarball loc tb
 
 extractTarball :: FilePath -> FilePath -> Property HasInfo
 extractTarball target src = toProp .
@@ -83,27 +84,28 @@ data Debootstrapped = Debootstrapped Debootstrap.DebootstrapConfig
 
 instance ChrootBootstrapper Debootstrapped where
 	buildchroot (Debootstrapped cf) system loc = case system of
-		(System (Debian _) _) -> Just debootstrap
-		(System (Ubuntu _) _) -> Just debootstrap
+		(Just s@(System (Debian _) _)) -> Right $ debootstrap s
+		(Just s@(System (Ubuntu _) _)) -> Right $ debootstrap s
+		Nothing -> Left "Cannot debootstrap; `os` property not specified"
 	  where
-		debootstrap = Debootstrap.built loc system cf
+		debootstrap s = Debootstrap.built loc s cf
 
 -- | Defines a Chroot at the given location, built with debootstrap.
 --
--- Properties can be added to configure the Chroot.
+-- Properties can be added to configure the Chroot. At a minimum,
+-- add the `os` property to specify the operating system to bootstrap.
 --
--- > debootstrapped (System (Debian Unstable) "amd64") Debootstrap.BuildD "/srv/chroot/ghc-dev"
+-- > debootstrapped Debootstrap.BuildD "/srv/chroot/ghc-dev"
+-- >	& os (System (Debian Unstable) "amd64")
 -- > 	& Apt.installed ["ghc", "haskell-platform"]
 -- > 	& ...
-debootstrapped :: System -> Debootstrap.DebootstrapConfig -> FilePath -> Chroot
-debootstrapped system conf = bootstrapped system (Debootstrapped conf)
+debootstrapped :: Debootstrap.DebootstrapConfig -> FilePath -> Chroot
+debootstrapped conf = bootstrapped (Debootstrapped conf)
 
 -- | Defines a Chroot at the given location, bootstrapped with the
 -- specified ChrootBootstrapper.
-bootstrapped :: ChrootBootstrapper b => System -> b -> FilePath -> Chroot
-bootstrapped system bootstrapper location =
-	Chroot location system bootstrapper h
-		& os system
+bootstrapped :: ChrootBootstrapper b => b -> FilePath -> Chroot
+bootstrapped bootstrapper location = Chroot location bootstrapper h
   where
 	h = Host location [] mempty
 
@@ -117,7 +119,7 @@ provisioned :: Chroot -> RevertableProperty
 provisioned c = provisioned' (propagateChrootInfo c) c False
 
 provisioned' :: (Property HasInfo -> Property HasInfo) -> Chroot -> Bool -> RevertableProperty
-provisioned' propigator c@(Chroot loc system bootstrapper _) systemdonly =
+provisioned' propigator c@(Chroot loc bootstrapper _) systemdonly =
 	(propigator $ propertyList (chrootDesc c "exists") [setup])
 		<!>
 	(propertyList (chrootDesc c "removed") [teardown])
@@ -125,18 +127,18 @@ provisioned' propigator c@(Chroot loc system bootstrapper _) systemdonly =
 	setup = propellChroot c (inChrootProcess (not systemdonly) c) systemdonly
 		`requires` toProp built
 	
-	built = case buildchroot bootstrapper system loc of
-		Just p -> p
-		Nothing -> cantbuild
+	built = case buildchroot bootstrapper (chrootSystem c) loc of
+		Right p -> p
+		Left e -> cantbuild e
 
-	cantbuild = infoProperty (chrootDesc c "built") (error $ "cannot bootstrap " ++ show system ++ " using supplied ChrootBootstrapper") mempty []
+	cantbuild e = infoProperty (chrootDesc c "built") (error e) mempty []
 
 	teardown = check (not <$> unpopulated loc) $
 		property ("removed " ++ loc) $
 			makeChange (removeChroot loc)
 
 propagateChrootInfo :: (IsProp (Property i)) => Chroot -> Property i -> Property HasInfo
-propagateChrootInfo c@(Chroot location _ _ _) p = propagateContainer location c p'
+propagateChrootInfo c@(Chroot location _ _) p = propagateContainer location c p'
   where
 	p' = infoProperty
 		(propertyDesc p)
@@ -145,12 +147,12 @@ propagateChrootInfo c@(Chroot location _ _ _) p = propagateContainer location c
 		(propertyChildren p)
 
 chrootInfo :: Chroot -> Info
-chrootInfo (Chroot loc _ _ h) = mempty `addInfo` 
+chrootInfo (Chroot loc _ h) = mempty `addInfo` 
 	mempty { _chroots = M.singleton loc h }
 
 -- | Propellor is run inside the chroot to provision it.
 propellChroot :: Chroot -> ([String] -> IO (CreateProcess, IO ())) -> Bool -> Property NoInfo
-propellChroot c@(Chroot loc _ _ _) mkproc systemdonly = property (chrootDesc c "provisioned") $ do
+propellChroot c@(Chroot loc _ _) mkproc systemdonly = property (chrootDesc c "provisioned") $ do
 	let d = localdir </> shimdir c
 	let me = localdir </> "propellor"
 	shim <- liftIO $ ifM (doesDirectoryExist d)
@@ -189,7 +191,7 @@ propellChroot c@(Chroot loc _ _ _) mkproc systemdonly = property (chrootDesc c "
 		return r
 
 toChain :: HostName -> Chroot -> Bool -> IO CmdLine
-toChain parenthost (Chroot loc _ _ _) systemdonly = do
+toChain parenthost (Chroot loc _ _) systemdonly = do
 	onconsole <- isConsole <$> mkMessageHandle
 	return $ ChrootChain parenthost loc systemdonly onconsole
 
@@ -214,7 +216,7 @@ chain hostlist (ChrootChain hn loc systemdonly onconsole) =
 chain _ _ = errorMessage "bad chain command"
 
 inChrootProcess :: Bool -> Chroot -> [String] -> IO (CreateProcess, IO ())
-inChrootProcess keepprocmounted (Chroot loc _ _ _) cmd = do
+inChrootProcess keepprocmounted (Chroot loc _ _) cmd = do
 	mountproc
 	return (proc "chroot" (loc:cmd), cleanup)
   where
@@ -234,10 +236,10 @@ provisioningLock :: FilePath -> FilePath
 provisioningLock containerloc = "chroot" </> mungeloc containerloc ++ ".lock"
 
 shimdir :: Chroot -> FilePath
-shimdir (Chroot loc _ _ _) = "chroot" </> mungeloc loc ++ ".shim"
+shimdir (Chroot loc _ _) = "chroot" </> mungeloc loc ++ ".shim"
 
 mungeloc :: FilePath -> String
 mungeloc = replace "/" "_"
 
 chrootDesc :: Chroot -> String -> String
-chrootDesc (Chroot loc _ _ _) desc = "chroot " ++ loc ++ " " ++ desc
+chrootDesc (Chroot loc _ _) desc = "chroot " ++ loc ++ " " ++ desc